ECL (Embeddable Common Lisp) is "an effort to modernize Giuseppe Attardi's ECL (ECoLisp) environment to produce an implementation of the Common Lisp language which complies to the ANSI X3J13 definition of the language". Most of the source code is distributed under the GNU GPL.

Current version is 9.6.2, as of jun 2009.License is not GPL, it is LGPL.Description is a bit misleading, since it is a full featured Common Lisp implementation with application delivery, native threads on all platforms, full ANSI compliance, unicode, generational garbage collector, compiler with multiple backends, and not only "effort".